Furnace or heat treatment chamber cooling means



June 23, 1931. E. L. SMALLEY FURNACE OR HEAT TREATMENT CHAMBER COOLING MEANS Original Filed Feb. 9, 1926 2 Sheets-Sheet affomg June 23, 1931. E. SMALLEY 1,811,158

FURNACE 0R HEAT TREATMENT CHAMBER COOLING MEANS Original Filed Feb. 9, 1928 2 Sheets-Shea 2 JmeMWzd n M fliibiwuy Patented June 23, 1931 UNITED STATES PATENT caries EDWIN L. SMALLEY, OF WHITEFISH BAY, WISCONSIN, ASSIGNOR T0 EEVI DUTY ELEC- i TRIO COMPANY, OF MILWAUKEE, WISCONSIN, A CORPGRATION OF WISCONSIN FURNACE OR HEAT TREATMENT CHAMBER COOLING MEAN S Original application filed February 9,

My invention relates broadly tofurnaces or heat treatment chambers and more particularly to a method of cooling. furnaces or heat treatment chambers and the material therein without subjecting the material within the furnace to the oxidizing action of free air.

This application is a division of my application Serial No. 253,199, filed February 9, 1928, for furnace or heat treatment chamber cooling means.

One of the objects of myinvention is'to provide a construction of cooling system for furnaces or heat treatment chambers by which material deposited within the furnace for coolin may be subjected to a predetermined temperature gradient over a prede termined time period.

Another object of my invention is to provide a method of cooling a charge within a furnace or chamber without the admission of free air to the furnace or chamber, reducing the amount of oxidization which would otherwise be present, with means for controllingthe rate of such cooling.

Still another object of my invention is to provide a system of cooling heat treatment furnaces or chambers by conduction and convection heat currents around the charge within the heat treatment furnace or chamber without subjecting the charge to contact with free air.

A further object of my invention is to provide a construction of heat treatment furnace or cooling chamber wherein heat within the chamber of the'furnace may be removed at a predetermined rate for. cooling the charge within the furnace by means of a plurality of fines located around'the charge within the furnace for conveying cooling air around the charge but out of contact therewith for absorbing heat from the charge at a predetermined rate.

Other and further objects of my invention reside in the arrangement of control apparatus for cooling means in heat treatment furnaces or chambers and the selective operation thereof for effecting the cooling of a charge along a predetermined temperature gradient over a definite time period.

1928, Serial No. 253,199. Divided and. this application filed April Serial No. 351,679.

chanical and electrical equipment for automatically controlling the heat and coolingtime-temperature cycle wherein the cooling system provides forced air circulation.

My invention is directed to a method of cooling furnaces or heat treatment chambers without the admission of free air to a furnace chamber or to a cooling chamber, either by'manual operation orcontrol of the cooling means, or automatically 'controlled means. By my invention when either a furnace or a cooling chamber is controlled automatically, it may be accomplished at a pre determined time-temperaturecycle; The ao-- tual invention consists of providing a cooling means which is mechanically and electrically interlocked with a heating means, whereby the cooling may be either retarded or accelerated either manually or automatically controlled. it

In numerous manufacturing processes at thepresenttime, such as in the heat treatment of certain kinds of rolled alloy steels or alloy castings; or in the manufacture of glassware and pottery, or other ceramic processes; or in the manufacture of malle-' ableiron, it is extremely desirable to control the time of heating to a predetermined temperature, holding that temperature until the work is thoroughly saturated and the change of structure in the work effected, and then subsequently to cool at a predetermined rate, or especially to accelerate the cooling without detriment to the work in process, and thus save considerable manufacturing time.

The time of cooling depends on the total absorbed heat in the charge of a furnace or cooling chamber, and the radiation from the furnace walls. In a given furnace, a light weight charge will cool faster than heavy weight charge, and this provides a means of cooling in a given time at a predetern ined rate, regardless of the weight of charge in the furnace.

Heretofore cooling has been effected by the introduction of free air into the furnace or cooling chamber, but this is highly undesirable, particularly in steel treatment, as it produces excessive oxidization. I

I-Ieretoforc it has been proposed to subject a selected charge to heat and then permit natural cooling thereof. t requires a con siderable time period to effect such natural cooling. In one case heretofore investigated to cool a six ton charge of miscellaneous steel castings by natural dissipation of the heat of the charge through the furnace walls, without admission of free air to the furnace chamber, required thirty-six hours. After the installation of the fines and cooling methods set forth herein, the same weight of charge was cooled without the admission of free air in 22 hours. The complete cycle consists of starting with the furnace comparatively cool, as at a temperature residue after the previous days run, bringing the charge up to an annealing temperature of 1600 to 1650 F, holding the furnace and charge until the charge is thoroughly and uniformly saturated at one of those temperatures, and then cooling as rapidly as possible to temperature below a visible heat, which is about 850 F. Below that temperature, castings may be subjected to free air circulation without excessive oxidi- Zation and without setting up strains in the castings that would be inherent if cooled too rapidly.

The necessity for a cooling chamber in combination with a furnace chamber may be shown by the fact that the furnace chamber, having a car in which there are heating elements on the car top in accordance with E. L. Smalleys Patent No. 1,547,623, dated July 28, 1925 for electrical furnaces, can heat a given weight of charge or mass density at the rate of three heats per day compared to furnaces without oar top heat requiring 12 hours. In order to effect economic operation of the furnace the cooling 3* period is advanced by the system herein described to render the furnace available to take a new charge within a reasonable time period.

Referring to the drawings in more detail, reference character 1 designates a supporting surface upon which foundation walls 2 are mounted and a rail system as represented at 3 over which the car 1- operates. The car l carries the material, represented in dotted lines 6, which is to be subjected to heat treatment. The car bottom may be heated the refractory brick lining 9. Suitable heat sealing plates 51 and52 may be disposed upon the surface structure and upon the car 4 for preventing leakage of heat from the interior of the furnace and preventing the admission of free air to the charge within the furnace. The space between plates 51 and 52 may be filled with any suitable sealin material, such as sand, for preventing leakage of air to the interior of the chamber.

In Figure 1, I have shown flues in the form of pipes 53 which extend vertically along the side walls of the furnace and connect with horizontally extending manifolds 54- at each side of the furnace. The vertically extending flues 53 are connected by risers 55 with'an upper horizontally extending manifold 56 which extends from a fan blower 57 driven by motor VI. The discharge of the air which is supplied from manifold 56 through risers 55 and fines 53 is exhausted at 59. Valve dampers 58 are positioned in the risers 55 and provide means for regulating the passage of cooling air through the fines 55. 1 7

Motor M can be operated manually by the opening and closing of a service'switch. As a means of automatically accomplishing a predetermined rate of heating, soaking and cooling, I show diagrammatically in Fig. 3, a wiring diagram of an electrically operated control system.

In Fig. 3, 60 is a movable armof a program controller, carrying a contact table 61, with electrical contact L and electrical contact H. 62 is the customary form of pyrometer needle of said program controlled or time-temperature-cycle controller, actuated by thermocouple located in the furnace chamber or in a cooling chamber (couple not shown). This movable pyrometer needle 62 is rotatable about a common center 63, which is concentric with the center; about which movable arm 60 is rotatable. 64: is a helical spring in tension, keeping lever arm 65 in constant contact with the perimeter of cam 66. Cam 66 can be made to make any required number of revolutions in any required time, as by 'means of a train of worm wheels and worms 68 and 69, respectively, driven by means of motor 7 O.

The contour of cam 66 can be made of any shape that is require to move the contact arm 60 across scale 71, and hold arm 60 contact 75.

at any position on scale. 71, and to reverse the movement of arm backward to the starting point, and cause any action in a predetermined time cycle.

The train of wormivheels and worms is drawn to scale. If motor revolves at the rate. of 1800 revolutions per minute, cam 66 withthe train as shown wouldrevolve .972 revolutions per week, or approximately four per month. 7

When the temperature in furnace 8, shown heated by electric heating coilsfiO, is below the required temperature, the thermocouple actuated needle 62 will be deflected until it makes contact'withl-L, thereby setting up a circuit through line 72 through the (301i 73 of a relay switch 74 and thereby closing Closing of contact 75 energizes C011 76 of main line contactor and closes contacts 77 thereby applying energy to coils 50 of furnace 8. The rising temperature of furnace causes thermocouple in furnace to become heated to a higher temperature and thus needle 62 of instrument is swayed away from contact L toward con-' tact H, but not in contact with either, and thus opens circuit through line 72, deenergizing coils 73 and 76, and thereby opening a main contacts 77.

hen furnace temperature again lowers, a recurrence of the same cycle of contacts and the same results will be effected. If the temperature of the furnace is such as to cause needle 62 to poise between contacts L If the generation of heat by coils 56 of .the furnace 8 is too great, the pyrometer needle 62 will be deflected to contact H, thereby setting up a current through line 78 and actuating coil 79 of relay 80, and closing relay contact 81. Line 82 thereby becomes energized, and by means of coil 83 of main contactor switches 84 closes the main contactor 8d and energizes motor circuits and causes the running of motor M. Motor M is connected to the fan blower. Starting the fan forces air circulation through the tines 53 of cooling chamber of Figs. 1 and 2. Circulation of air through such flues causes extraction of heat from the incorporated lines of Figsl and 2. \Vhen sufficient air has been blown through such flues as to cause a lowering of the ten perature in a cooling chamber or in a fur nace having flues in the wall of the furnace, the pyrometer needle 62 will be deflected downward away from H, thus opening the described line of circuits and stopping motor M.

If,for any cause, the cooling chamber or furnace has not cooled at a rate equal to the travel effected through cam action 66 such cam action will cause arm 60 with contact table 61 to travel toward the .low'temperature end of scale and subsequently contact l-Iwil connect with needle 62, thereby setting up energized circuit, same as above described, and starting motor M, with the same results as above described.

If the above method of operation is applied to acooling chamber to assist only in the acceleration of the cooling time, then relay 7 3 and contactor 77 and coils 50 in furnace 8 would be eliminated. I 6

If a furnace suchas 8 is heated by oil or gas, then by means of automatically con trolled valves, operated bya solenoid such as 73, of which there are numerous styles available today, relay 73 and contactor 76 can operate the valves of furnace for controlling the flow of gas or oil to give the same effect as to temperature change as is afforded by coils 50 in the diagram.

While I have described a certain preferred embodiment of my invention, I desire that it be understood that modification may be made and that no limitations are intended other than are imposed by the scope of the appended claims. j

. What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a heat treatmentapparatus, a cham treatment, a plurality of vertically *QXSGIlCl ing fiues positioned adjacent the interior walls of said chamber, said flues being disposed in'lateral planes spaced atinterva-ls along the length of said chamber, horizontally extending manifolds interconnecting opposite ends of saidfiues, one of said manifolds discharging to the atmosphere, and the other of said manifolds being arranged to receive a cooling fluid under pressure for distributing the cooling fluid through said flues and said manifoldsat a predetermined rate for lowering the temperature of the material being subjected to heat treatment over a predetermined time period.

3. A heat treatment apparatus comprising a chamber for material to be subjected to heat treatment, a plurality of vertically extending fiues positioned adjacent the interior walls of said chamber, a horizontally extending manifold positioned adjacent each side of the base of said chamber and connecting said fines, and a single manifold disposed centrally of said chamber interconnecting each of said fines, and means for forcing a cooling mixture through said flues and manifolds a predetermined rate for lowering the temperature of the material being subjected to heat treatment in accordance with a predetermined time period.

4. In a heat treatment apparatus, a chamber for material to be subjected to heat treatment, a plurality of fines substantially in the shape of an inverted Y disposed at intervals laterally along the length of said chamber, independent manifolds interconnecting the endsof said fines, the manifolds at the lower ends of said fines being interconnected and the manifolds at the upper ends of said fiues providing a passage for a cooling mixture through said fines, and means for controlling the rate of supply of a cooling mixture to said fines for lowering the temperature of the material being subjected to heat treatment over a predetermined time period without admission of free air to said chamber.

5. In a heat treatment apparatus, a chamber for housing material to be subjected to heat treatment, a plurality of Vertically extending flues positioned within said chamber at each side thereof, laterally extending flues interconnecting said first mentioned flues, rises connecting with each of said laterally extending fiues, horizontally extending manifolds connecting the upper extremities of said risers and the lower extremities of said fines, and means for forcing a cooling medium through said fines over a predetermined time interval for controlling the temperature of the material within said chamber.

6. In a heat treatment apparatus for high temperature heat treatment work, a chamber for material to be subjected to heat treatment, electrical means for heating said chamber, a plurality of flues positioned adjacent the interior walls of said chamber, manifolds interconnecting said lines, and means for forcing a cooling mixture through said manifolds and fines for lowering the temperature of said chamber over a predetermined timeperiod when said electrical means are deenergized.

7. In a heat treatment apparatus, for high temperature heat treatment work, a chamber for material to be subjected to heat treatm-ent, electrical means for heating said chamher, a plurality of tubular members extending through said chamber and means for automatically controlling the circulation of a cooling fluid through said tubular members according to the temperature of said heat treatment chamber for extracting heat from said chamber over a predetermined EDWIN L. sMAL'iEY. 

